java – 懒惰加载子项,里面有热切的集合

我想懒得加载森林的所有树木,并渴望加载一棵树的所有树叶.我的hibernate注释代码如下所示：

Forest.java

@Entity
@Table(name = "Forests")
public class Forest implements Comparable<Forest> {

      @Id
      @Column(name = "forestnumber",length=10,nullable=false)
      private String number;

      @OneToMany(fetch=FetchType.LAZY,mappedBy="forest")
      private Set<Tree> trees = null;

      // some other attributes and methods

Tree.java

@Entity
 @Table(name = "Trees")
 public class Tree implements Comparable<Tree> {

        @Id
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        @Column(name="tree_id",nullable=false)
        private int id;

        @ManyToOne(fetch = FetchType.EAGER)
        @JoinColumn(name = "forestnumber",nullable = false)
        @Fetch(FetchMode.JOIN)
        private Forest forest;

        @OneToMany(fetch=FetchType.EAGER,mappedBy="tree")
        @Fetch(FetchMode.JOIN)
        private Set<Leaf> leafs = null;

        // some other attributes and methods

Leaf.java

@Entity
 @Table(name = "Leafs")
 public class Leaf implements Comparable<Leaf> {

        @Id
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        @Column(name="leaf_id",nullable=false)
        private int id;

        @ManyToOne(fetch = FetchType.EAGER)
        @JoinColumn(name = "tree_id",nullable = false)
        @Fetch(FetchMode.JOIN)
        private Tree tree;

        // some other attributes and methods

我的问题：加载一个林并调用getTrees()方法会产生一组选择语句. Hibernate执行一个语句来获取所有树,并为每个树执行第二个语句以收集所有叶子.
在我看来,hibernate应该只生成一个语句,使用连接,同时收集树和叶子.

有人可以告诉我,我的问题的原因以及我如何解决它？
非常感谢！

再见：如果我将森林树的提取策略更改为EAGER,一切正常,只有一个语句.